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Metformin Might Protect Against High COVID-19 Mortality in Diabetes Patients

New studies offer both bad and good news for diabetes patients, when it comes to COVID-19. A nationwide analysis in England suggests the risk of death is significantly greater among novel coronavirus patients who have either type 1 or type 2 diabetes. On the other hand, a U.S. study suggests use of metformin is significantly protective. Here are more details.

YORK, UK – A nationwide analysis in England indicates that both type 1 and type 2 diabetes are independently associated with a significant increased odds of in-hospital death with COVID-19. Another recent study raises the possibility, however, that the most widely-used therapy for diabetes could provide some protection.

The report in The Lancet notes that, while diabetes has been associated with COVID-19-related mortality, the absolute and relative risks for type 1 and type 2 diabetes remained unknown. To help answer those questions, Public Health England-led researchers assessed the independent effects of diabetes status, by type, on in-hospital death in England in patients with COVID-19 during the period from March 1 to May 11, 2020.

The whole-population study included all individuals registered with a general practice in England who were alive on Feb 16, 2020. Of the 61.4 million individuals who were alive and registered with a general practice on Feb 16, 2020, 263,830 (0.4%) had a recorded diagnosis of type 1 diabetes, 2.8 million had a diagnosis of type 2 diabetes, 41,750 (0·1%) had other types of diabetes, and 58 million (94·8%) had no diabetes.

During the time period, researchers point out that 23,698 in-hospital COVID-19-related deaths occurred and that a third occurred in diabetes patients – 7,434 (31·4%) in people with type 2 diabetes, 364 (1·5%) in those with type 1 diabetes, and 69 (0·3%) in people with other types of diabetes.

The study team calculated unadjusted mortality rates per 100 000 people over the 72-day period at 27 (95% CI 27–28) for those without diabetes, 138 (124–153) for those with type 1 diabetes, and 260 (254–265) for those with type 2 diabetes.

“Adjusted for age, sex, deprivation, ethnicity, and geographical region, compared with people without diabetes, the odds ratios (ORs) for in-hospital COVID-19-related death were 3·51 (95% CI 3·16–3·90) in people with type 1 diabetes and 2·03 (1·97–2·09) in people with type 2 diabetes,” the authors write. “These effects were attenuated to ORs of 2·86 (2·58–3·18) for type 1 diabetes and 1·80 (1·75–1·86) for type 2 diabetes when also adjusted for previous hospital admissions with coronary heart disease, cerebrovascular disease, or heart failure.”

Meanwhile, a U.S. preprint study, led by University of Alabama Birmingham researchers, suggests that metformin could be a factor in diabetes patients with less dire outcomes.

The study team conducted a retrospective electronic health record data analysis of 25,326 subjects tested for COVID-19 between 2/25/20 and 6/22/20 at the University of Alabama at Birmingham Hospital, a tertiary health care center in the racially diverse U.S. South.Defined as the primary outcome was mortality in COVID-19-positive subjects.

The authors report that the  odds ratio of contracting COVID-19 was disproportionately high in Blacks/African-Americans (OR 2.6; 95%CI 2.19-3.10; p<0.0001) and in subjects with obesity (OR 1.93; 95%CI 1.64-2.28; p<0.0001), hypertension (OR 2.46; 95%CI 2.07-2.93; p<0.0001), and diabetes (OR 2.11; 95%CI 1.78-2.48; p<0.0001).

The study published in MedRxiv points out that diabetes was also associated with a dramatic increase in mortality (OR 3.62; 95%CI 2.11-6.2; p<0.0001) and “emerged as an independent risk factor in this diverse population even after correcting for age, race, sex, obesity and hypertension.”

“Interestingly, we found that metformin treatment was independently associated with a significant reduction in mortality in subjects with diabetes and COVID-19 (OR 0.33; 95%CI 0.13-0.84; p=0.0210),” the authors write, adding that their results “suggest that while diabetes is an independent risk factor for COVID-19-related mortality, this risk is dramatically reduced in subjects taking metformin, raising the possibility that metformin may provide a protective approach in this high risk population.”